A message containing letters fromA-Zis being encoded to numbers using the following mapping:'A' -> 1
'B' -> 2
...
'Z' -> 26
Given a non-empty string containing only digits, determine the total number of ways to decode it.Example 1:Input: "12"
Output: 2
Explanation: It could be decoded as "AB" (1 2) or "L" (12).
Example 2:Input: "226"
Output: 3
Explanation: It could be decoded as "BZ" (2 26), "VF" (22 6), or "BBF" (2 2 6).class Solution {
public int numDecodings(String s) {
int ways=0;
ways=countDecoding(s.toCharArray(),s.length());
return ways;
}
int countDecoding(char[] digits, int n){
// System.out.println(" digits "+disgits[0]);
// for base condition "01123" should return 0
// base cases
if (n == 0 || (n == 1 && digits[0]!='0'))
ret…

# Concepts of Computer Science

Data structures, Algorithms and system designs